A Simpler, Gentler Robotic Grip

A Simpler, Gentler Robotic Grip

Grab it: The robotic hand uses its embedded sensors to sense an object by touch; it then adjusts itself to get a good grip.

Dollar’s robotic hand consists of four fingers made out of a flexible, durable polymer. A single motor and spool tugs on the finger joints to open and close the hand. Each soft polymer finger contains embedded sensors, as detailed in the August 2009 online issue of Autonomous Robots. Dollar embedded two piezoelectric sensors–which report physical contact as a voltage response–into each of the four fingers through a molding process called shape deposition manufacturing (SDM). This process allows different materials to be deposited one layer at a time, so that sensors or other items can be set inside the material, which also protects those components.

“Traditional robot hand designs can be very complicated and comprise tens or hundreds of tiny parts that need to be painstakingly assembled,” says Andrew Ng, a 2008 TR35 winner and associate professor at Stanford University who works on household robots. “Dollar’s work gives robot designers a new and exciting way to build robot hands.” He adds that he is planning to apply the manufacturing technique to his own work.

“[Dollar’s] work is pushing forward on how we can have intelligent mechanics with low-level sensing and control,” says Kemp. “It will make things work better, without having to have a lot of sensing and computation. That’s exactly the type of thing we want right now, because we want robots in human environments.”

The system currently employs only one type of grasp–the “power” grip, which is useful for picking up some objects, such as a soda can, a ball, or a hammer. Next, Dollar hopes to add a “precision” grip, to enable the hand to pick up smaller objects, such as a pen.

Dollar’s former colleague Robert Howe will collaborate with Peter Allen, a professor at Columbia University, who has devised software to simplify robotic grasping, to improve the functionality of the hand. Dollar hopes the hand will eventually be used not just in robotics but also for prosthetics. Using “a stiff robotic hand to shake someone’s hand is a lot less human-like,” he says.